The invention relates to the production of solid products to be administered orally, in particular pharmaceutical products such as microgranules.
Medicaments to be swallowed, formed by a gelatine capsule enclosing microgranules with a maximum dimension of, for example, between 0.4 and 1.4 mm, are known. The aim is, by means of these microgranules, to obtain steady and prolonged release over time of a substance such as an active ingredient into the organism in order to reduce the number of doses taken by the patient. The production of the microgranules involves a stage in which the active ingredient in solution is fixed around inert grains, e.g. starch. This stage should make it possible to obtain on each grain one or more uniform homogeneous coating layers of predetermined thickness formed by a solution containing the active ingredient.
An existing system makes it possible to coat tablets of dimensions greater than 5 mm. These tablets are placed in a drum having perforations of a diameter less than 5 mm in order to avoid escape of the particles while at the same time allowing air to pass through the mass of tablets to be coated. With the drum rotating, the coating liquid is atomized onto the tablets. An air circuit allows elimination of the solvents and thus continuous formation of the coating layer.
As regards the microgranules, since these generally have a diameter of between 0.4 and 1.4 mm, which is thus markedly less than that of the tablets, it is impossible to place them in this drum, because the result would be that the microgranules would immediately escape via the perforations.
To mitigate this problem, one solution, which would be very difficult to implement and costly, would be to manufacture a drum with perforations less than 0.4 mm. Moreover, the small diameter of the apertures would entail a significant pressure drop in the air circuit.
Another solution, which is less costly, is to line the inside of the drum with a metallic cloth or screen with a mesh which prevents the passage of the microgranules. In this case, there are numerous constraints:
the fineness of the mesh makes the cloth very fragile and prone to tear, which entails the escape of the microgranules and hence the contamination of the air circuit and of the remainder of the installation;
the mesh is very rapidly obstructed by deposition of coating residues, necessitating frequent cleaning. The risk of clogging thus makes it necessary to reduce considerably the atomization rate of the coating solution; and
cleaning is made very difficult by the fact that the screen has to be removed. Moreover, even with thorough cleaning, there are numerous risks of contamination such that traces of a first active ingredient will be detected on the subsequent product.
One object of the invention is to provide a device suitable for the production of granules, in particular mini- or microgranules, which is easy to manufacture, entails a small pressure drop in the air circuit, reduces the risks that the product will escape into the installation, reduces the risks of cross-contamination and allows fixing or coating with a high output of coating or fixing substance.
With a view to achieving this object, the invention provides a device for the production of granules, in particular pharmaceutical granules, the device having a drum with peripheral apertures and a member for feeding the drum with coating or fixing substance, in which the drum has mutually parallel sections which define between them the apertures.
The width of the apertures thus depends on the spacing chosen for the sections. This spacing can be very small so as to obtain very narrow apertures suitable for the production of microgranules with a diameter between 0.4 and 1.5 mm, for example. This drum is easy to manufacture, including very narrow apertures. Moreover, the percentage of gaps in the wall of the drum is high, such that the pressure drop as any circulating air crosses the drum is reduced. The sections make the wall of the drum very strong. Any risk that the granules will escape into the installation is thus avoided. The sections are very easy to clean, in particular from the outside of the drum, thus reducing the risks of cross-contamination when fixing two different products in succession. Moreover, since the sections cause little clogging, fixing or coating can be carried out at a high rate of flow of coating or fixing fluid. Hence, when the products to be fixed or coated are sensitive to heat or humidity, the risks of degradation of the products are avoided. The device is particularly suitable for fixing or coating microgranules for medical applications comprising an active ingredient which should be released steadily and over a prolonged period into the organism.
It is advantageous if the sections have edges arranged opposite one another.
The edges thus make it possible to define the dimensions of the apertures very accurately.
It is advantageous if the edges delimit a flat face of each section, the said face facing the inside of the drum.
The flat faces of the sections thus define a flat internal face of the drum, which may be cylindrical, allowing the products fixed or coated to be given a very smooth surface.
It is advantageous if each section has a width that decreases from the inside towards the outside of the drum.
The drum is thus simple to clean, particularly from the outside of the drum, the lateral faces of the sections guiding a cleaning fluid towards the apertures between the sections for the purpose of unclogging them.
It is advantageous if each section has a triangular profile.
It is advantageous if the sections are rectilinear and parallel to an axis of rotation of the drum.
It is advantageous if the sections are curved.
It is advantageous if the drum has sectors which carry the sections and can be removed independently of one another.
This makes the drum easier to clean.
It is advantageous if the substance feed member is arranged in the drum.
It is advantageous if the substance feed member comprises an atomizer.
It is advantageous if the substance feed member is connected to a source of liquid.
It is advantageous if the substance feed member is connected to a source of compressed air.
It is advantageous if the device has means for the continuous supply of a gas to the interior of the drum and for forcing the gas to pass through the apertures from the inside towards the outside of the drum.
It is advantageous if the device has means for heating the gas upstream of the drum.
It is advantageous if the device is set up such that the gas passes through the apertures from the outside towards the inside of the drum.
The invention also provides a process for producing granules, in particular pharmaceutical granules, in which use is made of a device according to the invention.
Moreover, the invention provides granules, in particular pharmaceutical granules, which have been produced by means of a process according to the invention.
The invention also provides packaging such as a sachet or gelatine capsule comprising granules according to the invention.